2011 Annual Report 1a.Objectives (from AD-416) To improve our understanding of the mechanism(s) by which ovulatory follicle size affects pregnancy establishment and embryonic mortality. 1b.Approach (from AD-416) ARS – A student from Conapec will visit the Fort Keogh Livestock and Range Research Laboratory (LARRL) and evaluate the effects of serum estradiol and ovulatory follicle size on embryo quality & morphology, and pregnancy establishment & maintenance in beef cows. Conapec – members will evaluate effects of exogenous estradiol cypionate, equine chorionic gonadotropin, and temporary calf removal on ovulatory follicle size, and establishment / maintenance of pregnancy in large beef herds in Brazil. Information will be mutually shared between involved parties. 3.Progress Report This project (5434-31000-016-08S) is part of research that is conducted under National Program 101. The National Program Component for this project is: Understanding, Improving, and Effectively Using Animal Genetic and Genomic Resources, and has the goal of Improving Reproductive Efficiency in Livestock. Progress on this project included final hormonal analyses of blood samples and statistical analyses of data collected in FY2010. ARS Scientist traveled to Brazil to give two presentations and work with collaborating scientist and students on analyses and publication efforts. Two presentations were also given at regional and international meetings in the United States on this research by a Brazilian student. ADODR monitoring is via e-mail, discussions at professional meetings, and on-site visits.